Gall resistant nickel alloy



United States Patent 6 GALL RESISTANT NICKEL ALLOY John Trimble Eash, Westfield, NJ assignor to The International Nickel Company, Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 19, 1959, Ser. No. 800,589

8 Claims. (Cl. 75-171) The present invention relates to nickel alloys and, more particularly, to an improved malleable nickel alloy having improved resistance to galling and seizing together with a high combination of mechanical properties.

Heretofore, high nickel alloys have been widely employed in industry in applications demanding high strength together with high resistance to the deleterious elfects of many kinds of corrosive media. It is found that such prior nickel alloys had excellent corrosion resistance in many applications. Experience with the prior nickel alloys available to the art has indicated that many of these nickel alloys having great toughness and corrosion resistance have had an undesirable tendency toward galling and/or seizing in applications involving the rubbing or bearing of or upon the nickel alloy parts. The galling and/or seizing tendency found in nickel alloys resulted in removal of metal from the nickel alloy surface with accompanying damage to the surface and with the possibility of ultimate damage to the machine or which the nickel alloy working member was a part. This galling and/ or seizing tendency has required careful selection of materials and careful design of equipment in which corrosion resistant nickel alloys have been employed in bearing or rubbing contact with metals.

Although many attempts have been made to overcome the foregoing and other difficulties, none, as far as I am aware, has been entirely successful when carried into practice on an industrial scale.

It has now been discovered that a special maleable nickel alloy containing a special combination of ingredients possesses great toughness, strength and corrosion resistance together with improved resistance to galling and/ or seizing when used as a mechanical part in bearing or rubbing contact with metals.

It is an object of the present invention to provide a nickel alloy of special composition having improved resistance to galling or seizing.

It is a further object of the present invention to provide an improved malleable nickel alloy having a high combination of mechanical properties, corrosion resistance, and resistance to the effects of galling and seizing.

Other objects and advantages of the invention will become apparent to those skilled in the art from the following description:

Generally speaking, the present invention con-templates a graphitic malleable nickel alloy containing about 4% to 5.5% chromium, about 3.75% to 4.25% aluminum, about 0.25% to 0.75% titanium, about 0.4% to 0.85% carbon, and the balance essentially nickel, with the nickel content being about 84% to 91%. Generally, the alloy produced in accordance with the invention Will contain at least about 0.5%, e.g., about 0.4% to 0.6%, graphitic carbon, with the remainder of the carbon being present as a constituent of the matrix. The uncombined or graphi-tic carbon present in alloys contemplated in accordance with the invention is present as flake graphite.

The alloy beneficially contains a small amount of manganese, e.g., about 0.4% to 0.6% and a small amount silicon, e.g., about 0.2% to 0.4%, a small amount of r of iron, e.g., about 0.7% to 1.5%. Small amounts of residual deoxidizers should also be present in the alloy.

Usually, about 0.3% to about 0.1% magnesium and upv out changing the basic novel characteristics of the alloy.

Small amounts of incidental elements and impurities, e.g., phosphorus, sulfur, lead, bismuth, boron and lithium,- may be present in an amount up to a total of about 0.05%.

The alloys produced in accordance with the invention are hardenable by aging and in the age-hardened condition will have a hardness of at least about 280 BHN whereas forgings made from the alloys will have in the quenched condition a much lower hardness not exceeding about BHN. A satisfactory aging treatment comprises a heating to a temperature in the range of about 1700 to about 1850 F., quenching (preferably in oil) and a reheating at a temperature of about 1100 to 1150 F. for about 10 to 16 hours.

The alloy possesses a high combination of properties and usually exhibits mechanical properties within the approximate ranges given in the following table:

Age hardened 1 Tensile strength, p.s.i 135,000-175,000 Yield strength, p.s.i 555,000-125,000 Elongation, percent in. /inChes 36-24- BHN 280-355 1 Heat to 1800 F. for one hour, oil quench, age at 1100 F.

for 16 hours.

.As an example, one alloy (alloy No. 2) produced in accordance with the invention had, in the age hardened condition, a Brinell hardness of 311 with a yield strength (0.2% offset) of 101,750 p.s.i., a tensile strength of 160,800 p.s.i. and an elongation in two inches of 27.5%. Although magnesium generally and even preferably is employed as a deoxidizer in the production of the malleable alloy contemplated in accordance with the present invention and although magnesium generally is retained in the alloy in an amount of at least about 0.05%,"

graphite is present in the alloy in a flake form, i.e.,' the hot Worked alloy contains graphite flakes distributed throughout the nickel matrix. There are also two lightcolored constituents in the microstructure of the alloy which are believed to be carbides and which occur dis- 3 persed in the grain boundaries and in the matrix. The structure is associated With the improved resistance to galling. and/ or seizing which characterizes the alloys contemplated in accordance with the invention. V

It has been established that it is very important the compositions of alloys within the invention be maintained Within the ranges set forth hereinbefore and thatwhen any of the major constituents is present in an amount outside of the ranges given hereinbefore, markedly decreased properties are obtained. Thus, when the chromium is a less than about 4%, the graphite becomes coarserfland the resistance to galling decreases; and when the chromium exceeds about 5.5%, excess chromium carbides occur 7 i and the alloy becomes less resistant to g'alling; Again, i

when the aluminum is less than about 3 the hardness of Patented Mar. 7, 19 61 The alloy may also resistance is again reduced as the amount of free carbide is increased. The carbon content, in combination with the other constituents of the alloy, also contributes importantly to the properties of the alloy. Thus, when the carbon content is decreased below about 0.4%, the gall resistance is markedly reduced. On the other hand, when the carbon exceeds about 0.85%, the malleability of the alloy is deleteriously affected.

In order to obtain the best combination of malleability with strength and gall resistance, a carbon content of about 0.4% to about 0.6% is preferred. A carbon content of about 0.6% to about 0.85% provides increased resistance to galling and seizing in products produced from the alloy contemplated in accordance with the invention.

In order to give those skilled in the art a better understanding of the present invention, examples illustrating the analyses of preferred alloy compositions are given in the following table. The balance of the compositions in the table is essentially nickel.

As indicated hereinbefore, an unusual and distinctive property possessed by the alloys contemplated in accordance with the invention is that of high resistance to galling and seizing under frictional load. The testing procedure such as that described in the Bash and Lee US. Patent No. 2,568,014 was used to illustrate the high resistance to galling and/or seizing possessed by alloys contemplated in accordance with the present invention. This test procedure is as follows:

Test specimens one-half inch wide, about one-quarter inch thick, and several inches long were prepared from the test alloys. The galling or seizing tests were performed upon specimens which had been ground so that the grinding marks were parallel with the direction of movement of the movable specimen when the test speci mens were assembled in the fixture. Grinding was done with a silicate bonded aluminum oxide abrasive grinding wheel having a grit size of 46 mesh, using a 0.0005 cut at 60 feet per minute and 0.032" transverse feed per stroke. The grinding wheel was rotated at 2300 revolutions per minute, equivalent to about 6000 surface feet per minute. Two specimens of the alloy were fixed in face-to-face relationship in each of two slotted plates of a testing fixture. A third movable test specimen of the same alloy was then placed between the two fixed specimens and perpendicular thereto such that between the movable specimen and each of the fixed specimens two contacting surfaces /2" by /2" square and on directly opposite sides of the movable test specimen were provided. A spring load was then applied to the fixture in such manner that the contact surfaces were stressed in compression at the constant value of 3000 pounds per square inch during the course of the test. The assembled fixture was then placed in a compression test machine and a load was applied to the movable specimen to cause it to move perpendicularly to the fixed specimens and to keep the contact surface area constant at /2" by /2" square on each opposite side of said movable test specimen. The movable specimen Was forced through about one-half inch of travel at a speed of one-half inch per minute without lubrication. During the test, the load required to move the specimen was measured at regular in- 4 tervals over the distance traveled by the movable specimen. These data are shown the following table:

The shape of the curve employed upon plotting the data obtained in the aforedescribed manner is an indication of the anti-galling or anti-seizing properties of the alloy. Thus, if when load is plotted as ordinate against the distance traveled by the movable specimen as abscissa, a, curve having a sharply ascending slope is indicative of poor anti-galling properties while a curve which is nearly horizontal with the abscissa or which actually slopes downwardly is indicative of good anti'galling properties. Thus, it has been found that bearing alloys such as a cast leaded -10-10 bronze and nickel-antimony bronze produced very flat curves and were resistant to galling in the test. Similarly, electroplated chromium and a nickelcopper-silicon alloy known to have high gall resistance in service showed excellent anti-galling and anti-seizing properties when tested in the aforedescribed manner.

By reference to the foregoiing table, it may be seen that alloys within the scope of the invention exhibited very good anti-galling properties. On the other hand, tests conducted on otherwise similar alloys but containing either greater or lesser amounts of any of the essential alloying ingredients than those required in accordance with the present invention, i.e., chromium, titanium, carbon and aluminum exhibit inferior results when tested under the same conditions.

The alloy contemplate in accordance with the invention can be produced in any of the furnaces normally used in melting nickel alloys, e.g., the direct or indirect arc furnace, the induction furnace, etc.

In order to illustrate a satisfactory method for producing the alloy of the present invention, the following illustrative example is given:

A melt of nickel alloy was established in an induction furnace using nickel-carbon stock to provide a carbon content in the melt of about 0.75%. Alternatively, nickel stock may be melted with additions of carbon in the form of crushed electrode butts, graphite, etc., to provide the nickel-carbon melt. Additions of aluminum, chromium and titanium were made to the melt to provide final contents of about 4%, 5% and 0.5%, respectively, in the final alloy. The melt was then deoxidized with additions of 0.5% manganese, 0.25% silicon, 0.05% magnesium and 0.02% zirconium. The deoxidized metal was then cast into ingots. The ingots were cropped, heated at 2150" F. and forged into bars.

In breaking down commercial sized ingot castings, it is preferred that an extrusion process be employed as this method offers the most convenient means of producing the alloy in commercial size and in malleable form.

The alloy of the invention possesses a unique combination of properties which make it useful for a wide number of applications where wrought nickel articles may be used. The alloy may also be used in the form of precision castings, in which case the castings desirably are produced under a protective atmosphere. Not only and wear but the alloy is readily machinable and canbe ground to provide an excellent surface. The unusual combination of properties possessed by the alloy makes it suitable for use in many applications, including nuts and bolts, screws in conveyors, shafts, valves, pump and pump parts, gaskets and scraper blades.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the inventionand appended claims.

I claim:

1. A nickel-base alloy consisting essentially of about 4% to about 5.5% chromium, about 3.75% to about 4.25% aluminum, about 0.25% to about 0.75% titanium, and about 0.4% to about 0.85% carbon, said alloy being characterized by the presence of flake graphite, by forgeability, by high resistance to galling and by a high combination of mechanical properties.

2. A nickel-base alloy consisting essentially of about 4% to about 5.5% chromium, about 3% to about 5% aluminum, about 0.25% to about 1% titanium, about 0.4% to about 0.85 carbon, up to about 0.4% silicon,

up to about 0.6% manganese, up to about 1.5% iron,

up to about 0.1% magnesium, up to about 0.02% zirconium, up to about 2% copper, and up to about 1% cobalt, said alloy being characterized by the presence of flake graphite, by forgeability, by high resistance to galling and by a high combination of mechanical properties.

3. A nickel-base alloy according to claim 2 having a carbon content of about 0.4% to about 0.6% and characterized by an improved combination of malleability and gall resistance.

4. A nickel-base alloy according to claim 2 having a carbon content of about 0.6% to about 0.85% and characterized particularly by improved gall resistance.

5. A nickel-base alloy consisting essentially of about 5% chromium, about 4% aluminum, about 0.5% titanium, about 0.75% carbon, about 0.25% silicon, and about 0.02% zirconium, said alloy being characterized by the presence of flake graphite, by torgeability, by '1 high resistance to galling and by a high combination of mechanical properties. i

6. The method for hardening a nickel-base alloycona sisting essentially of about 4% to about 5 .5 chromium,

about 3% to about 5% aluminum, about 0.25% to r about 1% titanium, about 0.4% to about 0.85% carbon,

up to about 0.4% silicon, up to about 0.6% manganese, up to about 1.5% iron, up to about 0.1% magnesium, up to about 0.02% zirconium, up to about 2% copper, and up to about 1% cobalt which comprises heating said alloy to a temperature in the range of about 1700 to about 1850 F., quenching, and reheating said alloy at a temperature in the range of about 1100 to about 1 l F. for about 10 to about 16 hours to provide in said alloy a hardness of at least about 280 BHN.

7. The method for hardening a nickel-base alloy consisting essentially of about 4% to about 5.5 chromium, about 3.75% to about 4.25% aluminum, about 0.25% to about 0.75% titanium, and about 0.4% to about 0.85% carbon which comprises heating said alloy to a temperature of about 1800 F., oil quenching, and reheating said alloy at a temperature of about 1100 F. for about 16 hours to provide in said alloy a hardness of at least about 280 BHN.

8. The method for hardening a nickel-base alloy consisting essentially of about 5% chromium, about 4% aluminum, about 0.5% titanium, about 0.75 carbon, about 0.25% silicon, and about 0.02% zirconium which comprises heating said alloy to a temperature of about 1800 F., oil quenching, and reheating said alloy at a temperature of about 1100 F. for about 16 hours to provide in said alloy a hardness of at least about 280 BHN.

633,870 Germany Aug. 10, 1936 Australia Jan. 26, 1956 UNITED STATES PATENT UFFICE CERTIFICATION OF QORRECTION Patent; No. 2 974 038 March 1961 John Trlmiole Eash I I It is hereby certified that error a ears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 42 for "malealole" read malleable column 2 line 4 for 'O.,3%" read 0.03% column l line S'L for foregoiing read foregoing llne 46 for "-o0noemplate read contemplated Signed and sealed this 22nd day of August 1961,,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

2. A NICKEL-BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT 4% TO ABOUT 5.5% CHROMIUM, ABOUT 3% TO ABOUT 5% ALUMINUM, ABOUT 0.25% TO ABOUT 1% TITANIUM, ABOUT 0.4% TO ABOUT 0.85% CARBON, UP TO ABOUT 0.4% SILICON, UP TO ABOUT 0.6% MANGANESE, UP TO ABOUT 1.5% IRON, UP TO ABOUT 0.1% MAGNESIUM, UP TO ABOUT 0.02% ZIRCONIUM, UP TO ABOUT 2% COPPER, AND UP TO ABOUT 1% COBALT, SAID ALLOY BEING CHARACTERIZED BY THE PRESENCE OF FLAKE GRAPHITE, BY FORGEABILITY, BY HIGH RESISTANCE TO GALLING AND BY A HIGH COMBINATION OF MECHANICAL PROPERTIES. 